Not that many people are left in here, but I figured someone might be interested in my findings this morning. I got the Tamron 10 days ago and have been shooting it on my D7100 and borrowed a friends D600 and got some pretty impressive results. I have various posts on here about them. I had many people ask me on my FB page about the D300. I dusted ol betsie off this morning and went out to give it a whirl. There is a chance ol betsie might just be tired, she is pretty close to 150K clicks and she is pretty beat up. AF acquisition did not exist. Tracking was quite poor and IQ was just not there. Here are 2 sort of keepers, but the hit rate just wasn't there. https://www.flickr.com/photos/coastalconn/14126150089/https://www.flickr.com/photos/coastalconn/14312803105/

I used to shoot with the old Tamron 200-500 that was also f6.3 at 500mm and it behaved much better. It felt like the D300 exhibited the same behavior as the early Canon mounts that was reported online..